In recent years, fabric softening has become an integral part of the home laundry routine. Many different composition and use varieties have been proposed over the past twenty years or so. Some of the more recent trends include the "clear" craze characterized by concentrated, reduced packaging products.
A wide variety of fabric softening agents have been described in the patent literature. For example, JP 3033271 (Kao) discloses a transparent water-based softening agent having an antistatic effect. The agent comprises 12-35% wt. of a water-insoluble cationic textile-softener and 1-8 wt. % of (poly)oxyalkylene Guerbet alcohol branched monohydric alcohol. The softening agent is used for household treatment of clothing to give an antistatic effect and to restore softness.
JP 2300381 (Kao) describes a softening finishing agent for clothes which is practically transparent and contains 12-25 wt. % of a cationic softening base agent, 1-10 wt. % of an oil liquid substance having more than one ester bond and more than one hydroxyl group in the molecule, and having a viscosity of 20-2,000 cps. at 20.degree. C., and 1-5 wt. % of a polyether compound, or derivative, of polychain type with av. mol. wt. 5,000-2,000,000 and which is an alkylene oxide adduct of a compound having more than three active hydrogens as the essential components.
U.S. Pat. No. 3,892,669 (Unilever) discloses a clear fabric softening composition containing 2-20% wt. of a solubilized tetraalkyl quaternary ammonium salt having two short and two long chain alkyl groups. Apart from being visually clear, the composition is physically stable and remains clear when diluted, or after being subjected to a temperature range of 0.degree.-125.degree. F. The composition also imparts a soft and pleasing handle to fabrics which would otherwise tend to be harsh and stiff.
EP 82457 (Hoechst) refers to a clear liquid fabric softener concentrate comprising 26-40 wt. % of a cationic fabric softener (I), 0.01-8 wt. % of an anionic surfactant (II), 0.01-8 wt. % of a nonionic dispersant (III), 3-30 wt. % of 1-3 C alkanol (IV) and the balance being water and optional perfumes, colorants and other additives. The softener (I) is especially a quaternary ammonium salt or an imidazolinium salt. Component (II) is preferably of formula Me(CH.sub.2).sub.n CH(SO.sub.3 Y)CH.sub.2 Me, ArSO.sub.3 Y, R.sub.5 O(CH.sub.2 CH.sub.2 O).sub.m SO.sub.3 Y or R.sub.6 CH.dbd.CHCH.sub.2 SO.sub.3 Y where n is 11-14; Ar is p-R.sub.4 -phenyl; R.sub.4 -R.sub.6 are 10-15 C alkyl; m=0-5; Y is Na, K or NH.sub.4. Component (III) is preferably an ethoxylated alkylphenol or fatty alcohol. The compositions have good storage stability, exhibiting no thickening or solids precipitation on standing for long periods.
U.S. Pat. No. 3,887,476 (Ashland Oil Inc.) describes a fabric softener concentrate dispersion containing 65-85 wt. % of a quaternary ammonium salt and 35-15 wt. % of a lower alkanol.
EP 435476 (Hoechst) refers to laundry soft-rinsing concentrates consisting by weight of 30-70% cationic softener, 5-50% nonionic softener, 5-20% nonionic dispersant, 5-30% 1-3 C alkanol, 5-30% liquid glycol, polyglycol or alkyl ether thereof, water and optional perfume and dyestuffs, up to 100%. The concentrates are easily dispersed in cold water without gel formation.
U.S. Pat. No. 4,751,009 (Akzo) discloses a clear, stable, single phase fabric softener containing by weight 10-16% anionic surfactant (containing an at least 8 C alkyl), 20-35% cationic surfactant, 15-25% propylene glycol, 8-10% of an alkali metal sulphonate, and not more than 30% H.sub.2 O.
Notwithstanding prior efforts, as represented by the foregoing, there is still a need for liquid fabric softening compositions which demonstrate improved softening effects and/or other desirable properties, e.g. increased shelf-life and ease of pourability.